The utility of a computer system could be enhanced by providing a better user interface. Since widespread application of personal computers (PC), the user interface of the computer system has been dramatically improved. Early PCs use input devices such as keyboard and mouse. However, significant improvements on microprocessors, available memory and programming functions have made contributions to improvement of user interface design and development of user-friendly graphic operating systems and hardware. A specific field of the improvement of the user interface technology relates to detection of an object approaching the user interfaces, also referred to as proximity detection. The proximity detection is the detection on the object including a physical object, user's hand or finger.
An existing interactive display device is provided with an infrared scanning light source and an infrared camera mounted at the bottom of its housing. The infrared scanning light source emits the infrared rays to periodically scan a user interface. When a finger of a user is approaching the user interface, it can reflect the infrared rays emitted by the infrared scanning light source, and the reflected infrared rays are received by the infrared camera. The position of the user's finger can be obtained through an analysis and processing of the computer system, and then corresponding response operation can be executed according to the position information. Since the infrared scanning light source needs a certain scanning radius during the scanning, the interactive display device is relatively high, causing that the interactive display device is of a large size and unfavorable for transport.